reftex-auto-recenter-toc

reftex-auto-recenter-toc is a variable defined in `reftex-vars.el'.
Its value is

frame

Documentation:
Non-nil means, turn automatic recentering of *TOC* window on.
When active, the *TOC* window will always show the section you
are currently working in. Recentering happens whenever Emacs is idle for
more than `reftex-idle-time' seconds.

Value t means, turn on immediately when RefTeX gets started. Then,
recentering will work for any TOC window created during the session.

Value 'frame (the default) means, turn automatic recentering on only while the
dedicated TOC frame does exist, and do the recentering only in that frame. So
when creating that frame (with `d' key in an ordinary TOC window), the
automatic recentering is turned on. When the frame gets destroyed, automatic
recentering is turned off again.

This feature can be turned on and off from the menu
(Ref->Options).

You can customize this variable.